# Custom networks and values

This section will cover importing bootstrapper IDs, chain ID,
and network ID. This will allow you to import custom values
for a chain that is not in the default configuration.

If you have a custom network you can export `CELESTIA_CUSTOM`, which will
look something like:

```bash
export BRIDGE="/ip4/<ip-address>/tcp/2121/p2p/<node-ID>"
export GENESIS_HASH=<genesis-hash>
export NETWORK=<network-name>
export CELESTIA_CUSTOM="${NETWORK}:${GENESIS_HASH}:${BRIDGE}"
```

Query your node ID [from the CLI](/operate/data-availability/light-node/advanced#find-your-node-id).
These values with examples would look like:

```bash
export BRIDGE="/ip4/151.115.14.33/tcp/2121/p2p/12D3KooWKEeRtzVMPUdxYsZo2edqps6mS67n6LT5mPdULSkPSxBQ"
export GENESIS_HASH=580B3DFF8A7C716968161D91116A1E171F486298D582874E93714E489C9E6E88
export NETWORK=custom
export CELESTIA_CUSTOM="${NETWORK}:${GENESIS_HASH}:${BRIDGE}"
```

For an archival bridge node, include the genesis field in `CELESTIA_CUSTOM`.
Setting only `CELESTIA_CUSTOM="${NETWORK}"` omits that field and prevents
archival startup with a `genesis hash not found` error. A non-empty
`GENESIS_HASH` must identify the network's genesis block: archival startup
uses it as `SyncFromHash`, so an incorrect hash prevents syncing from the
correct starting point. An explicitly empty field, as in
`CELESTIA_CUSTOM="${NETWORK}:"`, starts archival sync from height 1 instead.

Bridge nodes prune by default. To retain historical headers and original
data, pass `--archival` every time you start the node. Archival nodes still
trim redundant erasure-coded data outside the storage window.

Then, start your node with:

```sh
celestia <node-type> start [flags...]
```

For an archival bridge node:

```sh
celestia bridge start --archival [flags...]
```